Known as a conventional working object grinding method is one irradiating the inside of a planar working object with a laser beam, so as to remove an outer edge portion of the working object, and grinding a main face of the working object after removing the outer edge portion (see, for example, Patent Literature 1). Such a working object grinding method aims to prevent knife edges from occurring at an outer edge of the working object.
Patent Literature 1: Japanese Patent Application Laid-Open No. 2006-108532